This invention relates to a fastening structure using a plastic fastener, and more particularly to an improved fastening structure of the type which permits repeated attachment and detachment.
The basic function of plastic fasteners is to fasten two parts together. However, a fastener which is merely capable of fastening two parts together is often not sufficient. For example, when such a fastener is used for mounting a radiator grille to a vehicle body, the fastener must have a structure which allows the radiator grille to be detached and re-attached when necessary for repairs or the like.
A prior art fastener which by and large satisfies these requirements is disclosed in Japanese Patent Application Public Disclosure No. 99435/1980. This known fastener is used for example for mounting a radiator grille on a vehicle body, and is composed of a rotatable shaft, a head with a special (e.g. rhombic) configuration provided on one end of the shaft, and an anchor-shaped catch member provided on the other end. Meanwhile, an aperture for engaging the catch member is provided in advance in the vehicle body, while the radiator grille is provided with an aperture large enough to allow the head to pass through when the shaft is rotated by 45.degree.. Fastening of the radiator grille to the vehicle body using this fastener is carried out by firstly bringing the fastener head into registration with the aperture in the radiator grille and inserting it, then turning it by 45.degree. so as to make it inextractable. Next, the fastener's catch member is inserted into the aperture in the vehicle, thus joining the radiator grille to the vehicle body. The procedure for detaching the radiator grille and for re-using the fastener involves considerable trouble. That is to say, a slot is provided in advance on the fastener head, and a screwdriver of some such means is inserted into this slot and the head turned by 45.degree., and when the head registers with the aperture in the radiator grille, it is extracted. In this way the grille and the body are separated. Next, in order to re-join them, a screwdriver is passed through the aperture and the head is turned by 45.degree., whereafter it is passed through the aperture. Otherwise, the fastener is detached from the vehicle body and the joining operation is repeated in accordance with the fastening procedure described above. Of these two operations, the latter requires less skill than the former, and the re-joining can be carried out relatively easily. However, this kind of fastener is used in automobiles etc. and must, therefore, be capable of providing an engagement of sufficient strength to withstand vibrations and shocks, so it is not an easy matter to remove the catch member from the vehicle body.
There has been a great need for a fastener which permits the attachment and detachment operations involved in automobile maintenance etc. to be performed more simply.